How to resolve the algorithm Hello world/Line printer step by step in the Racket programming language

Published on 12 May 2024 09:40 PM
#Racket

How to resolve the algorithm Hello world/Line printer step by step in the Racket programming language

Table of Contents

Problem Statement

Cause a line printer attached to the computer to print a line containing the message:   Hello World!

A line printer is not the same as standard output. A   line printer   was an older-style printer which prints one line at a time to a continuous ream of paper. With some systems, a line printer can be any device attached to an appropriate port (such as a parallel port).

Let's start with the solution:

Step by Step solution about How to resolve the algorithm Hello world/Line printer step by step in the Racket programming language

Source code in the racket programming language

#lang racket
(define (print text)
  ;; try lpr first
  (define lpr-exe (find-executable-path "lpr"))
  ;; otherwise use a special file
  (if lpr-exe
    (with-input-from-string (~a text "\n") (λ() (void (system* lpr-exe))))
    (with-output-to-file #:exists 'append
      (case (system-type) [(windows) "PRN"] [else "/dev/lp0"])
      (λ() (displayln text)))))
(print "Hello World!")

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